JPH0544766A - Vibration damping device - Google Patents

Abstract

PURPOSE:To make this device applicable to a small apparatus and a small structure by controlling a vibration with a viscous variation in an electroviscous fluid or liquid crystal, and reducing the extent of damping force made by a flow of fluid, while lessening an amount of oil consumption. CONSTITUTION:This vibro-damping device is provided with an inner cylinder 3, an outer cylinder being fitted free of slide motion at the outside of this inner cylinder 3, two sealing members 4, 5 sealing both ends of these inner and outer cylinders 2, 3, a clearance part 6 being formed in space between both these inner and outer cylinders 2 and 3, two electrodes 7, 8 being installed as opposed to this clearance part 6, and an electroviscous fluid or liquid crystal being filled up in this clearance part 6, through which it controls each impression voltage of these electrodes 7, 8 according to a state of vibrations.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is widely used in industrial machines, transportation machines such as vehicles, and other various devices or structures.
The present invention relates to a vibration damping device for damping vibration of a vibration system.

[0002]

2. Description of the Related Art Conventionally, as a vibration damping device, a working fluid such as oil or air is used, a piston is provided in a damper case, and two fluid chambers are formed in the damper case by the piston. It is known that an orifice that communicates with a fluid chamber is provided, an operating shaft fixed to a piston extends inside and outside a damper case, and a vibrating body is connected to the operating shaft.

However, the vibration damping characteristics of the above conventional vibration damping device are fixed depending on the shape of the orifice and the characteristics of the working fluid. Therefore, when the vibration damping device is used in a vibration system that differs from its original design conditions,
Optimal vibration damping characteristics cannot be obtained. Further, when the vibration damping device is used in a vibration system whose vibration state changes with time, a vibration system formed by coupling a plurality of vibrations, or the like, the vibration cannot be effectively damped.

In order to solve the above-mentioned problems, an electrorheological fluid is filled in a damper case, an electrode is arranged in an orifice portion which communicates between two fluid chambers, and a voltage is applied between the electrodes to generate the electrorheological fluid. An apparatus has been proposed which controls viscosity and makes damping force variable (for example, Japanese Patent Laid-Open No. 1-266334).

[0005]

However, in the above-described conventional vibration damping device using the electrorheological fluid, since the electrorheological fluid flows through the orifice having a small gap,
There is a problem that the pressure difference between the two fluid chambers is large and the damping force becomes too large, and the amount of fluid used is large, so that it cannot be applied to a vibration damping device for small equipment and small structures.

The present invention solves the above problems, and controls vibration by changing the viscosity of a fluid to reduce the damping force due to the flow of the fluid and reduce the amount of oil used, thereby reducing the size. An object of the present invention is to provide a vibration damping device that can be applied to equipment and small structures.

[0007]

To this end, the vibration damping device of the present invention comprises an inner cylinder 3, an outer cylinder 2 slidably fitted outside the inner cylinder 3, an outer cylinder 2 and an inner cylinder 3. Sealing members 4 and 5 for sealing both ends, a gap portion 6 formed between the outer cylinder 2 and the inner cylinder 3, electrodes 7 and 8 provided to face the gap portion 6, and inside the gap portion 6. And an electrorheological fluid to be filled in, and the voltage applied to the electrodes 7 and 8 is controlled according to the state of vibration. Liquid crystal may be adopted instead of the electrorheological fluid. It should be noted that the numbers added to the above configuration are for comparison with the drawings for easy understanding, and the configuration of the present invention is not limited thereby.

[0008]

In the present invention, a voltage corresponding to the vibration state of the device or structure 11 is applied to the electrodes 7 and 8, and when a voltage is applied between the electrodes 7 and 8, the electroviscosity in the gap 6 is increased. An electric field orthogonal to the fluid is formed, and the electrodes 7 and 8
The viscosity of the electrorheological fluid sandwiched between is increased or decreased. Therefore, since the viscous resistance between the outer cylinder 2 and the inner cylinder 3 is adjusted, the vibration damping characteristic of the device or the structure 11 can be adjusted very easily. Further, when liquid crystal is used instead of the electrorheological fluid, the state such as the direction and arrangement of the liquid crystal molecules sandwiched between the electrodes 7 and 8 changes, and the viscosity of the liquid crystal increases or decreases.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a sectional view showing an embodiment of the vibration damping device of the present invention, and FIG. 2 is a sectional view taken along the line AA of FIG.

The vibration damping device 1 of the present invention comprises an inner cylinder 3 and an outer cylinder 2 slidably fitted outside the inner cylinder 3. Both ends of the outer cylinder 2 and the inner cylinder 3 are seals such as O-rings. An annular gap 6 between the outer cylinder 2 and the inner cylinder 3 is sealed by the members 4 and 5.
Is formed. Cylindrical electrodes 7 and 8 are formed on the inner peripheral surface of the outer cylinder 2 and the outer peripheral surface of the inner cylinder 3 so as to face the gap 6. The electrodes 7 and 8 are provided via an insulating material when the outer cylinder 2 and the inner cylinder 3 are made of a metal material, and are directly provided when they are made of an insulating material such as resin.

A reservoir chamber 9 is formed inside the inner cylinder 3, and the reservoir chamber 9 communicates with the gap portion 6. Then, the electro-rheological fluid is filled in the gap 6 and the reservoir chamber 9. The reservoir chamber 9 is for replenishing the electrorheological fluid in the gap 6 when it leaks to the outside.
It is not always necessary if the seal structure is secured. The inner cylinder 3 is fixed on the support 10, and the equipment or structure 11
Is supported by the support body 10 via the spring 12 and is also supported by the outer cylinder 2 via the spring 13.

Next, the operation of the present invention having the above structure will be described. The vibration of the device or the structure 11 is detected by a vibration detection sensor such as an acceleration sensor, and a voltage according to the magnitude of the vibration is applied to the electrodes 7 and 8 by an electronic control device (not shown). When a voltage is applied between the electrodes 7 and 8, an electric field orthogonal to the electrorheological fluid in the gap portion 6 is formed, and the viscosity of the electrorheological fluid sandwiched between the electrodes 7 and 8 is increased or decreased. Therefore, since the viscous resistance between the outer cylinder 2 and the inner cylinder 3 is adjusted, the vibration damping characteristic of the device or the structure 11 can be adjusted very easily. In addition,
If tuning is performed so that the primary vibration is absorbed when no voltage is applied and the applied voltage is appropriately controlled, 2
Vibrations higher than the following can be easily suppressed. In the present invention, unlike the conventional case, since the electrorheological fluid does not pass through the orifice and the electrorheological fluid itself is not in a flowing state, it is possible to reduce the damping force due to the electrorheological fluid.
The amount of fluid used can be reduced, it can be applied to small devices and structures, and vibration control over a wide range is possible.

Next, an embodiment of the electrorheological fluid will be described. The Winslow effect of electrorheological fluid is
It is disclosed in US Pat. No. 2,417,850, in which solid particles (dispersoids) are suspended in an electrically insulating liquid (dispersion medium) between two electrodes, a so-called electrorheological fluid is used. Filling and applying a voltage between both electrodes results in an increase in fluid viscosity due to the effect of an external electric field. Not only can this viscosity be externally controlled by the magnitude of the external electric field, but the excellent effect of extremely good responsiveness can be expected.

Explaining the embodiments of the electrorheological fluid, the electrically insulating liquid as the dispersion medium may be any electrically insulating liquid and is not particularly limited, but, for example, mineral oil or synthetic oil may be used. Yes, more specifically, naphthenic mineral oil, paraffinic mineral oil, polyalpha-olefin, polyalkylene glycol, silicone, diester, polyol ester, phosphate ester, silicon compound, fluorine compound, polyphenyl ether, alkylbenzene, synthetic hydrocarbon. And so on. The viscosity range of these electrically insulating liquids is 5 to 300 CP at 40 ° C.
Are preferred.

Further, the porous solid particles as the dispersoid are
Commonly used ones are not particularly limited, and examples thereof include silica gel, hydrous resin, diatomaceous earth, alumina, silica-alumina, zeolite, ion exchange resin, and cellulose. These porous solid particles are
Usually, a particle size of 10 nm to 200 μm is 0.1 to 50
Used in a percentage by weight.

In order to enhance the polarization promoting effect, water,
A polarization promoter such as polyhydric alcohol, acid, salt or base is added. In particular, it is preferable to use the porous solid particles, which are dispersoids, in a mode that facilitates dielectric polarization. Examples of the polarization promoting agent include polyhydric alcohols and partial derivatives thereof. As polyhydric alcohol, dihydric alcohol,
Trihydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, glycerin,
Examples thereof include propanediol, butanediol, pentanediol, hexanediol and the like. Examples of preferable polyhydric alcohols include triethylene glycol and tetraethylene glycol.

Further, the partial derivative of polyhydric alcohol is a partial derivative of polyhydric alcohol having at least one hydroxyl group, and some of the terminal hydroxyl groups of the above polyhydric alcohol are methyl group, ethyl group and propyl group. , Partial ethers substituted with an alkyl-substituted phenyl group (the number of carbon atoms of the alkyl group substituted with a phenyl group is 1 to 25), etc., and some of the terminal hydroxyl groups are esters with acetic acid, propionic acid, butyric acid, etc. And partial esters thereof.

These polyhydric alcohols or their partial derivatives are usually used in an amount of 1 wt% to 100% based on the porous solid particles.
wt%, particularly preferably 2 wt% to 80 wt% may be used. If the addition amount is less than 1 wt%, the ER effect is small, and if it exceeds 100 wt%, the current easily flows, which is not preferable. The amount of water or polyhydric alcohol used is usually 1 to 100% by weight with respect to the porous solid particles.

Next, the acid, salt and base components will be described. As the acid component, sulfuric acid, hydrochloric acid, nitric acid, perchloric acid, chromic acid, phosphoric acid, inorganic acids such as boric acid, or acetic acid, formic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, oxalic acid, malonic acid, etc. Organic acids are used.

As the salt, a metal or a basic group (N
H ₄ ⁺ , N ₂ H ₅ ^+, etc.) and an acid group, and any of these can be used. Among them, polyhydric alcohols, those which dissolve in a system of polyhydric alcohol partial derivatives and dissociate, for example, those which form typical ionic crystals such as alkali metal and halides of alkaline earth metals,
Alternatively, alkali metal salts of organic acids and the like are preferable. LiCl, NaCl, KCl, MgCl, etc.
₂ , CaCl ₂ , BaCl ₂ , LiBr, NaBr, K
Br, MgBr ₂ , LiI, NaI, KI, AgN
O ₃ , Ca (NO ₃ ) ₂ , NaNO ₂ , NH ₄ NO ₃ , K ₂
SO ₄ , Na ₂ SO ₄ , NaHSO ₄ , (NH ₄ ) ₂ SO ₄
Alternatively, there are metal salts of alkali acids such as formic acid, acetic acid, oxalic acid and succinic acid.

Examples of the base include alkali metal or alkaline earth metal hydroxides, alkali metal carbonates, amines, etc., and polyhydric alcohols, polyhydric alcohol partial derivatives, or polyhydric alcohols and / or polyhydric alcohols. Those that dissolve in the system of the alcohol partial derivative and water to dissociate are preferable. As this kind of base, NaOH, KOH, Ca
(OH) ₂ , Na ₂ CO ₃ , NaHCO ₃ , K ₃ PO ₄ , N
a ₃ PO ₄ , aniline, alkylamine, ethanolamine and the like. The above-mentioned salt and base can be used in combination.

The above-mentioned acids, salts and bases are capable of increasing the polarization effect, but when used in combination with a polyhydric alcohol and / or a polyhydric alcohol partial derivative, the polarization effect is further enhanced. The total amount of electrorheological fluid is 0.01 wt% to 5w.
It is preferable to use it at a ratio of t%. If it is less than 0.01 wt%, the ER effect is small, and if it exceeds 5 wt%, it becomes easy to energize and power consumption increases, which is not preferable.
Further, when an acid, salt or base component is added to the electrorheological fluid of this example, it is necessary that the partial esterified product of the polyhydric alcohol is not hydrolyzed.

Further, a dispersant is used to make the dispersion state of the porous solid particles in the dispersion medium uniform and stable. For example, sulfonates, phenates, phosphonates, succinimides, amines, esters, nonionic dispersants and the like are used, and specifically, magnesium sulfonate, calcium sulfonate, calcium phenate, calcium phosphonate, Examples include polyisobutenyl succinimide, sorbitan monooleate and sorbitan sesquioleate. These are usually 0.1
Used at a rate of ~ 15% by weight. However, the dispersant may not be used when the dispersibility of the solid particles is good.

Further, additives such as an antioxidant, an antiwear agent, a corrosion inhibitor, a friction modifier, an extreme pressure agent and an anti-packaging agent may be added.

In the examples of the present invention, an electrorheological fluid comprising alkylbenzene as a dispersion medium, silica gel as a dispersoid, and triethylene glycol as a polarizing agent is used.
Polybutenyl succinimide is added as a dispersant, and 2.6-di-t-butylphenol is added as an antioxidant.

Next, another embodiment of the present invention will be described. In this embodiment, liquid crystal is adopted instead of the electrorheological fluid, and when a voltage is applied between the electrodes 7 and 8, the gap 6 is formed.
An electric field that is orthogonal to the liquid crystal inside is formed, the state of the direction and arrangement of the liquid crystal molecules sandwiched between the electrodes 7 and 8 is changed, and the viscosity of the liquid crystal is increased or decreased. It is played.

The liquid crystal used in the present invention may be a commercially available product, for example, azo type, azoxy type, benzoic acid phenyl ester type, cyanobiphenyl type, cyanoterphenyl type, cyclohexylcarboxylic acid phenyl ester type,
Phenylcyclohexane system, biphenylcyclohexane system, phenylpyrimidine system, phenyldioxane system, cyclohexylcyclohexane ester system, cyclohexylethane system, cyclohexene system, alkylalkoxytran system, alkenyl system, 2,3-difluorophenylene system, cyclohexylcyclohexane system, bicyclooctane system It is possible to use a liquid crystal of a system, a cubane system, a dicyanohydroquinone system, a cyanothiophenyl ester system, an azomethine system, or the like.

However, the azomethine type is stable,
It is not so preferable because the thickening effect is small. Further, if necessary, additives such as an antioxidant, an antiwear agent, a corrosion inhibitor, and a friction modifier may be added. The above liquid crystals may be used alone or as a mixture. Preferably, various liquid crystal substances are mixed and used in order to improve liquid crystal characteristics. As a concrete example of the liquid crystal, a trade name RDX-4069
A liquid crystal (manufactured by Rodick) was used.

In this embodiment, the following effects are obtained as compared with the above-mentioned embodiment using the electrorheological fluid. Since the applied voltage is small, local damage due to discharge etc. is reduced and the life of the device is extended, the gap between the electrodes can be narrowed and the device can be downsized, and the battery can be used as a power source. Becomes

Since there is no concern about sedimentation of solid particles,
No decrease in thickening effect and clogging of filter. Control is easy because the effect of shear rate is small. Hard to deteriorate.

[0031]

As apparent from the above description, according to the present invention, an outer cylinder, an inner cylinder slidably fitted in the outer cylinder,
A seal member that seals both ends of the outer cylinder and the inner cylinder, a gap portion formed between the outer cylinder and the inner cylinder, an electrode provided so as to face the gap portion, and the gap portion is filled. Since the voltage applied to the electrode is controlled according to the state of vibration, the vibration is controlled by the change in the viscosity of the electrorheological fluid or the liquid crystal, and the damping force due to the flow of the fluid is also provided. Can be made small, and the amount of fluid used can be made small, so that it can be applied to small devices and small structures, and vibration control over a wide range becomes possible.

Further, since the electrodes are formed on the inner peripheral surface of the outer cylinder and the outer peripheral surface of the inner cylinder, it becomes easy to form the electrodes at a predetermined interval.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a vibration damping device of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1 as seen from the direction of the arrow.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Vibration damping device, 2 ... Outer cylinder, 3 ... Inner cylinder, 4, 5 ... Seal member O-ring 6 ... Gap, 7, 8 ... Electrode, 9 ... Reservoir chamber, 10 ... Support 11 ... Equipment or structure , 12, 13 ... Spring

Claims (2)

[Claims] 1. An inner cylinder, an outer cylinder slidably fitted to the outside of the inner cylinder, a seal member for sealing both ends of the outer cylinder and the inner cylinder, and between the outer cylinder and the inner cylinder. A gap portion to be formed, an electrode provided so as to face the gap portion, and an electrorheological fluid filled in the gap portion, and the voltage applied to the electrode is controlled according to a vibration state. Vibration damping device. 2. An inner cylinder, an outer cylinder slidably fitted to the outside of the inner cylinder, a seal member for sealing both ends of the outer cylinder and the inner cylinder, and between the outer cylinder and the inner cylinder. A vibration characterized by comprising a gap portion to be formed, an electrode provided so as to face the gap portion, and a liquid crystal filled in the gap portion, wherein an applied voltage to the electrode is controlled according to a vibration state. Damping device.